Pump



L. A. ANDREWS.

PUMP.

APPLICATION FILED FEB. 5, 920. 1,431,355 Patentd Oct. M), 1922.

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LOUIS'A. ANDREWS, OF NEWTON UPPER FALLS, MASSACHUSETTS.

' PUMP.

Application filed February 5, 1920. Serial No. 356,800.

volves the provision in a pump, more especially the hand operated typeand suitable for pumping air, water, or in fact any fluid, of means formaintaining a tight fit between the piston and the inner wall of thecylinder.

In pumps of this character the piston is made to include a flexiblecup-shaped or socalled bucket washer which usually consists of leather.This washer is provided for the purpose of producing, by reason of itsshape and flexibility, a tight lit between the piston and the inner wallof the cylinder, or pump barrel, as well during the upward or suctionstroke, when the fluid is drawn into the cylinder, as during thedownward or compression stroke, when the fluid is compressed and forcedout of the cylinder. It has been found in practice, however, that theflexible washer, especially after prolonged use, has a tendency to lose,to a certain extent, its original form by shrinkingvor flexing inwardlyaway from the inner wall of the cylinder. The new form or shaperesulting from this inward llexure is assumed bythe washer particularlyduring the upward or suction stroke with consequent leakage of air pastthe piston to partially break --down the suction created thereby, andthus impair the operation of f the pump. It is also evident that in theabsence of means for correcting this deformation of the bucket washerthere might also be leakage of air past the piston during thecompression stroke, but this diliculty would be less pronounced due tothe tendency of the air under compression to force the bucket washerAagainst the cylinder wall.

The present invention, therefore, involves the provision of means formaintaining a tight fit-'between the cylinder and the piston during boththe suction and compres- .sion strokes.

In accordance with one form of the in-y vention the cylinder or barrelof the pump has a diametrical enlargement at its lower end, and thepiston in cludes in its construction a bucket washer.,Loosely suspendedbelow the piston, or carried thereby, and spaced below the bucketwasher, is a circular piece or cone, constituting an expansion f member,the base of which is nearly equal in diameter to the interior of thecylinder, and the upper-diameter of which is preferably less than theinterior of the bucket washer so that this member will fit into thewasher. The loosely mounted member or cone is, in this construction,preferably held in spaced .relation to the bucket washer by means of aspringinterposed between them. When the piston reaches the bottom of thecylinder at the end of the compression stroke, the circular piece orcone is moved against the bucket washer thereby forcing or crowding thebucket washer outwardly, expanding it into the enlargement of thecylinder. Then, as the piston is raised upwardly from this position, thebucket washer engages the lower end of the cylinder and is reducedthereby to the size ofv the inner Working diameter of the cylinder whichproduces a snug lit between the washer and the inner wall of thecylinder. In this way the bucket washer is reformed after eachcompression stroke so that it will tightly fit the pump cylinder andprevent leakage of air past the piston not only during the suctionstroke, but as well during the compression stroke.

In the specific embodiment of this form of my invention hereinafterdescribed, the piston rod has a shoulder spaced from its lower end, andthe piston is mounted on the piston rod below this shoulder. In order tosecure the piston in place there is provided a tube which is mountedonthe piston rod below the piston, and a nut which is screwed on thelower end of the piston rod to press the tube against tlie piston andfirmly hold the latter in position against the shoulder. The device forexpanding the bucket washer into the-enlargement ofthe cylinder at theend of each compression stroke consists of a conical expansion memberwhich is loosely mounted on the tube, and. is held in spaced relationtothe bucket Washer by means of a helical spring which presses theexpanding member downupon the nut, the conical member having its largestand lowest diameter slightly less than the interior of the cylinder.

washer are means for normally holding them in spacedrelation, and theblock and washer kare so constructed and arranged as to be brought intoengagement on the down stroke of the piston to cause the block to bearagainst portions of the washer to hold them in contact with the innerwall of the cylinder. rlihus a tight joint will be produced between thepiston and the cylinder by positive action of the expanding memberagainst the bucket washer throughout the compression stroke. lit will beunderstood that in this form of my invention the cylinder or pump barrelmight be of the usual construction, that is to say of uniform diameterthroughout. 1t will be evident, however, that where the expanding devicewould'be brought to bear against the Washer throughout the down strokeof the piston without expansion of the washer at the end of the strokebeyond the size of the working diameter of the cylinder, the devicewould be effective merely to maintain a tight joint during thecompression stroke since means are provided for normally holding theexpansion device and the bucket washer apart during the up stroke orsuction stroke of the piston. 1n one application of my invention,therefore, it will be seen that both the forcing or crowding outwardlyof the bucket washer against the cylinder Wall by the expansion memberto maintain a tight fit during the compression stroke, and the expansionof the bucket washer into a diametrcal enlargement at the base of thepump barrel at the end of the 'compression stroke to effect a tight fitduring `both the suction and compression stroke, may be combined in onestructure by a suitable construction, arrangement and proportioning ofthe parts. For example, in order that the expansion member may bearagainst the bucket washer during the compression stroke, becomingeective at the beginning of the stroke and continuing until the end ofthe stroke when the washer is expanded into the enlargement, the meansfor holding the bucket washer andvexpansion member in spaced relation,such as a spring, may be made sufficiently light so that the pressureduring compression will be suliicient to force the expansion deviceagainst the bucket washer and hold it in this posif press them againstthel cylinder wall, where' upon, at the end of the piston stroke, theexpansion device -would be moved upwardly by contact with the base ofthe pump the remainder of the distance separating it from the washer' toexpand the latter into the enlargement.

The invention is illustrated in the accompanying drawings inapplication, as an example, to a pump the cylinder of which has anenlargement at the base for the expansion therein of the bucket washerto a diameter exceeding the diameter of the cylinder of the pump. 1nthese drawings- Fig. l is a sectional elevation of the pump showing thepiston construction;

Fig. 2 vis a similar sectional view showing the piston in position atthe end of the down stroke;

Fig. 3 is a sectional view of the intake valve;

Fig. 4 is a cross section of a portion of this valve, and y Fig. 5 is 'asectional view illustrating a modified form of `construction for theenlargement at the base of the pump.

The cylinder 1 has its lower end attached to a base 2 in a well knownmanner, and is provided with a piston 3' and a piston rod 4f. The pistonhas a leather bucket washer 5 of well known form, held in place by atube 6 and a nut 7 on the threaded stem 9 of the piston rod 4.' Thepressure of the nut against the end of the tube 6 fastens the piston andwasher in place on the piston rod.

Loosely mounted on this tube 6 is an expansion member or block, 10 aportion of whose outer periphery is shaped like the rustrum of a coneand Whose largest diameter is almost equal to that of the interior ofthe cylinder l. A helical spring 11 mounted on the tube 6 servesnormally to retain the cone l0 upon the nut 7.

1n the base 2 below the end of the cylinder l is formed a conicalenlargement l2, a flat door 13 and a central well 14. Atene side llt) ,,threaded lower end of the head 2() is screwed a threaded thimb-le 24whosey lower end is screwed into the boss 15, a washer 25 acting torender both screw-surfaces: air-tight. The valve itself consists of arubber tip 2G having a metal stem 27. which descends through a hole 29in the thimble 24 for the better guidance of' the valve. As shown inAFig. 4, one or more holes 30 are also formed through the floor of thethimble to permit air to freely pass through the same. Similarly/thebase of the pump is provided with means for permitting the outflow ofair compressed in the cylinder. For this purpose the base 2 is formedwith a, boss 31 which is tapped to receive anoutletvalve 32 providedwith means for connecting thereto a flexible hose 33 to conduct the airto the point of vdelivery in the usual manner, and the opening in theboss is connected with the well 14 by a conduit 34. The valve 32 mayhave a construction similar to the intake valve, the de tails of whichare shown in Fig. 3, except that the valve member 26 would be arrangedto operate in the reverse manner to that when functioning as an intakevalve, as will be readily understood; or the valve 32 may be of anyconventional construction.

' The operation of the pump is as follows: `When the piston is depressedto its lowest point, the cone 10 comes in contact with the floor 13 andis forced up into engagement with the bucket washer 5, thereby forcingor crowding the latter outward into the enlargement 12, as shown in Fig.2. Then when the piston is raised, the cone-remains on the floor 12until the washer is free thereof, but as thev piston further rises, theeX- panded washer is contracted by its engagement with the cylinder-endand made to snugly fit the cylinder. This will be the operation of thepump where the spring 11 is made sufficiently strong to withstand the-pressure of the air compressed in the cylinder below the piston duringthe down stroke to hold the cone 10 and bucket washer' 5 in spacedrelation, this result being made possible also. by the fact that thecone 10 is made somewhat smaller in diameter than the inside diameterofthe cylinder so that air may escape past it-during the down stroke. Itwill be understood, however, that this operation may be modified byproviding a lighter spring and a closer t of the cone l() within thecylinder so that during the down stroke the air pressure will fo'rcethe-cone 10 against the washer and hold the downwardly proform a conicalenlargement 12, and this conical enlargement made to terminate in anaued and screwed upon a boss composing a part of the base 2. It is, ofcourse, operated in the same manner as the construction first described,but on account of its superior lightness, I prefer this construction forvery many purposes.

What l claim is:

1. A pump comprising a cylinder, and a piston movable therein, thecylinder havlng a diametrical enlargement at its lower end, the pistonhaving a bucket washer', and a cone loosely carried by the piston spacedbelow the Abucket washer, the base of the cone being nearly equal indiameter to the interior of the cylinder, whereby, when the pistonreaches the bottom of the cylinder, the cone is made to expand thebucket washer into said enlargement.

2. A pump comprising a cylinder, and a piston movable therein, thecylinder having a diametrical enlargement at its lower end, and thepiston having a bucket washer, and a circular member loosely suspendedbelow the piston, the lower diameter of said mem.- ber being nearlyequal to that of the cylinder and its upper' diameter being less thenthat of the interior of the bucket washer, a spring being provided fornormally retaining said member spaced from the piston.,

3. A pump comprising a cylinder having an enlargement at its lower end,a piston, a piston rod having a shoulder spaced from its lower end, thepiston being mounted on the rod below said shoulder, a tube mounted onthe piston rod below the piston, a nut on the lower endof the piston rodpressing the tube and piston rmly upward against said shoulder, aconical member loosely mounted on said tube, and a helical springmounted on said tube and pressing the conical member down on said nut,said conical member having its largest and lowest diameter slightly lessthan that of the interior of the cylinder, the piston having a bucketwasher.

4. In a device of the class described, the combination with a pistonrod, of a pair of washers on said rod, a leather washer between thewashers of said pair, a block carried by said rod and adapted to move?t0- ward the pair of washers and bear against portions of the leatherwasher for producvnular section 28 which is internally threading a tightjoint, and a spring interposed.

between the block and the washers for nora crowding position with'theleather washer.

ln a device of the class described, the

combination With a piston rod, of a primary and an auxiliary Washer onsaid piston rod, the auxiliary Washer being of less diameter than theprimary washer, a cup-like leather Washer between the primary andauxiliary Washers, a slidable block carried by the rod under the washersand being adapted to engage the leather washer for crowding the sameoutwardly, and a spring between the block and the auxiliary Washer fornormally holding said block in an inoperative position with respect tothe leather Washer.

6. In a device of the class described, a.

piston rod carrying a piston and an eX- panding block, said pistonincluding a cupped, flexible Washer, and means interposed bet-Ween theblock and the Washer for normally holding them in spaced relation, saidblock and washer being constructed and arranged to be brought intoengage- 7. A pump comprising a cylinder, a piston rod, and a pistonmounted on said rodand movable Within the cylinder, said pistonincluding a cupped, flexible Washer, and said rod having loosely mountedthereon an expanding device normally held in spaced relation to saidWasher, said expanding device being constructed and arranged to moveagainst said Washer at the end of the piston stroke to expand portionsof the Washer against the cylinderV Wall thereby to maintain a tightjoint.

ln testimony that l claim the foregoing invention, I have hereunto setmy hand this 2nd day of February, 1920.

Louis A, ANDREWS.

